Slip assembly for a well tool

ABSTRACT

An improved slip assembly for a well tool having a mandrel wherein unitary slips are positively held to an upper and lower cone by integral dovetail coacting engaging surfaces with a centering sleeve engaging each slip for maintaining the longitudinal movement of all slips in unison as they are moved outwardly and inwardly with the centering sleeve including an opening for each slip whereby the slip may be connected to the cones by inserting the slips from the interior of the sleeve openings thereby allowing improved slip construction. A tubing anchor utilizing said slip assembly and having a mandrel with the upper cone threadably engaged to the mandrel and a lower cone mounted for rotation on the mandrel but longitudinally secured thereto by shear pins and a bow spring connected to the upper cone for actuating the movement of the slips.

United States Patent Current et a1.

[ 1 Feb. 22, 1972 [54] SLIP ASSEMBLY FOR A WELL TOOL [72] Inventors: James H. Current; Marlon D. Kilgore, both of Houston, Tex.

[s2 U.S.CI. nos/21o, 166/139 [51] Int. Cl ..E2lb 23/00 [58] Field oiSearch ..166/l38-140,216, 166/217 [56] References Cited UNITED STATES PATENTS 2,633,201 3/1953 Clark 166/ 140 2,825,410 3/1958 Brown 166/216 3,058,526 10/1962 Douglass et al.... 166/217 3,180,419 4/1965 Cochran et al. 166/120 3 ,279,542 10/1966 Brown 166/139 3,361,209 1/1968 Edwards, .lr. 166/120 3,456,723 7/1969 Current et a1 166/ 120 3,467,184 9/1969 Young ..l66/l38 Primary ExaminerJames A. Leppink Attorney-James F. Weller, Jefierson D. (iiller, William A. Stout, .Paul L. DeVerter, 11, Dudley R. Dobie, Jr. and Henry W. Hope [57] ABSTRACT An improved slip assembly for a well tool having a mandrel wherein unitary slips are positively held to an upper and lower cone by integral dovetail coacting engaging surfaces with a centering sleeve engaging each slip for maintaining the longitudinal movement of all slips in unison as they are moved outwardly and inwardly with the centering sleeve including an opening for each slip whereby the slip may be connected to the cones by inserting the slips from the interior of the sleeve openings thereby allowing improved slip construction. A tubing anchor utilizing said slip assembly and having a mandrel with the upper cone threadably engaged to the mandrel and a lower cone mounted for rotation on the mandrel but longitudinally secured thereto by shear pins and a bow spring connected to the upper cone for actuating the movement of the slips.

4 Claims, 8 Drawing Figures PAIENIEDFEB22 I972 SHEET 2 OF 3 BACKGROUND OF THE INVENTION Generally, the use of dovetail connections between the slips and the cone of a slip assembly and the use of a centering sleeve to prevent the slips from cockingand locking is shown in US. Pat. No. 3,456,723. However, in order to assemble the slips to the upper and lower cones by the dovetail connections it has been necessary to make the dovetail connections to the cones a separate piece which was attached to the cone by screws. Such connections were not entirely satisfactory as they could become loosened during use. One feature of the present invention is the provision of an improved slip assembly having dovetail connections between the slips and cones in which the dovetail connections are integrally made with the cones and the slips so as to be stronger yet which can be easily assembled.

Another feature of the present invention is the use of the improved slip assembly of the present invention in a tubing anchor. Tubing anchors for anchoring the lower end of tubing in a well bore such as shown in US. Pat. Nos. 2,715,442 and 2,825,410 are old. The improved slip assembly of the present invention as used in a tubing anchor provides an improved tubing anchor which is particularly rugged and dependable and wherein the parts are positively actuated ineither setting or retracting operations and which can be released safely in an emergency.

SUMMARY One feature of the present invention is the provision of an improved slip assembly for a well tool having a mandrel by providing a plurality of unitary slips and wedge-shaped slips supporting means surrounding the mandrel and positioned at each end of the slips whereby when the supporting means are moved relative to each other the slips are expanded outwardly and dovetail shaped coacting engaging surfaces are provided on each end of the slips and on the supporting means at the end of the slips which are integrally made with the supporting means and the slips for strength and dependability. A centering sleeve is provided slidably at all times to and surrounding the mandrel with engaging means on the sleeve and each slip for maintaining the longitudinal movement of all of the slips in unison as they are moved outwardly and inwardly. The centering sleeve includes an opening for each slip whereby the slips may be assembled to the supporting means by inserting the slips through the sleeve openings while the mandrel is withdrawn to engage the dovetail shaped coacting engaging surfaces.

Another feature of the present invention is providing a slip assembly in which the parts are locked together and cannot be taken apart without first removing the mandrel whereby the assembly will not accidentally come apart in a well.

Still another feature of the present invention is the provision of a tubing anchor utilizing the slip assembly of the present invention wherein the tubing anchor includes an upper cone threadably engaged to the mandrel with a lower cone mounted for rotation on the mandrel but longitudinally secured thereto with friction means connected to the upper cone for actuation of the slip assembly with means between the upper cone and the mandrel for limiting upward movement of the cone relative to the mandrel.

Still a further feature is the provision in the tubing anchor of the lower cone being longitudinally secured to the mandrel by shear means to provide a safe emergency release.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is an elevational view, partly in cross section, showing the top half of a tubing anchor utilizing the improved slip assembly of the present invention,

FIG. 1B is a continuation of FIG. 1A,

FIG. 2 is an elevational view of the centering sleeve of the slip assembly showing a slip in dotted outline positioned therein,

FIG. 3 is a cross-sectional view taken along the line 33 omitting the slips,

FIG. 4 is a cross-sectional view taken along the line 33 of FIG. 2, but showing the slips positioned in the centering sleeve,

FIG. 5 is a perspective view of a slip used in the slip assembly of the present invention,

FIG. 6 is an elevational view in cross section showing the method of assembly of the slips to the cones, and

FIG. 7 is an exploded elevational view in cross section showing the method of inserting the mandrel into the assembly.

- DESCRIPTION OF THE PREFERRED EMBODIMENT While the slip assembly of the present invention may be used in various types of well tools, it will be described by way of example only, in use in an improved tubing anchor which is also a feature of the present invention.

Referring now to the drawings, and particularly to FIGS. 1A and 1B, the tubing anchor of the present invention is generally indicated by the reference numeral 10 and generally includes a tubular mandrel l2 and a slip assembly generally indicated by the reference numeral 14. The upper end of the mandrel I2 is adapted to be connected to a well tubing 16 such as by threads.

The slip assembly 14 includes an upper wedge-shaped slip supporting means such as an upper cone l8 and a lower wedge-shaped slip supporting means such as lower cone 20. Integral dovetail shaped coacting engaging surfaces 22 and 24 are provided on the upper cone l8 and the lower cone 20,

respectively, to engage and coact with dovetail shaped engaging surfaces 26 and 28 (FIG. 5) respectively on a plurality of unitary slips 30. Thus as the upper and lower cones l8 and 20 are moved towards each other the slips 30 are expanded outwardly and conversely as the cones I8 and 20 are retracted from each other the slips are positively moved inwardly by the coaction of the dovetail coacting surfaces between the slips 30 and the cones l8 and 20.

The upper cone 18 is threadably engaged to the mandrel 12 by thread 32 and frictional means such as bow springs 35 are connected to the upper cone 18 and adapted to engage a well casing (not shown) to provide rotational movement between the upper cone I8 and the mandrel 12 as the mandrel is rotated thereby longitudinally moving the upper cone l8 relative to the mandrel 12. A sea] 33 is provided between the upper cone l8 and the mandrel 12 above the threads 32 to prevent filth and debris from settling on the threads 32 and assures that the slip assembly 14 may be retracted when desired. The lower cone 20 is attached to the mandrel 12 such as to allow relative rotation between the lower cone 20 and the mandrel 12 but prevent normal relative axial movement between the lower cone 20 and mandrel 12 for actuation of the slips 30 as the upper cone 20 is moved. Thus, the lower cone 20 may be attached to the mandrel 12 by one or more shear means such as shear pins 34 positioned in an annular groove 36 in the mandrel I2. The shear pins 34 also act to provide the additional function of an emergency release. That is, if the tubing anchor cannot be released by rotating the mandrel 12 opposite to the setting direction, the mandrel is pulled upwardly sufficiently to shear pins 34 and the lower cone 20 is immediately released and the slips 30 retracted, all without impact so that unnecessary damage to the anchor 10 is avoided.

Referring now to FIGS. 1A, and 2-5, a centering sleeve 40 is provided which is slidably positioned on and surrounding the mandrel l2. Engaging means are provided on the sleeve 40 and each slip such as ears 42 on the sleeve 40 which coact with slots 44 on the sides of the slip 30. The ears 42 and slots 44 thus allow the slips 30 to move outwardly and inwardly relative to the centering sleeve 40 but maintains the longitudinal movements of all of the slips 30 in unison as they are moved thereby preventing the dovetail coacting surfaces between the cones I8 and 20 and the slips 30 from binding and stopping actuation of the slip assembly 14.

In US. Pat. No. 3,456,723, the slips 30 were attached to the cones I8 and 20 by meshing one of the dovetail connections between the slips 30 and one of the cones, but because of the tapers involved, the dovetail connection on the second cone was required to thereafter be attached to the cone by screws and could not be made integrally with the cone. However, such screwed connections were subject to becoming loose and causing failure of operation. It is to be noted in FIGS. 2-4 and 6--7 that the centering sleeve 40 includes an opening 46 between adjacent ears 42 to allow the slips 30 to be inserted from the inside of the centering sleeve 40 outwardly into place in the centering sleeve 40 with the ears 42 engaging the slots 44 on the slips 30 and the coacting dovetail surfaces 26 and 28 on the slips 30 would then engage the coacting dovetail shaped coacting engaging surfaces 22 and 24, respectively, on the upper and lower cones l8 and 20, respectively. By this method of assembly, the dovetail engaging surfaces 22 and 24 on the cones l8 and 20 can be made integrally with the cones l8 and 20 and thereby provide a much stronger slip assembly 14.

The method of assembly of the slip assembly is best seen in FIGS. 6 and 7. The slips 30 are first placed in the openings 46 between adjacent cars 42 of the centering sleeve 40 (FIG. 4). The upper cone l8 and the lower cone 20 are placed at the ends of the centering sleeve 40. It is to be noted from FIG. 6 that the mandrel 12 is not in place in the cones l8 and 20 and the centering sleeve 40 thereby allowing the slips 30 to be retracted into the interior of the centering sleeve 40 (FIG. 4) in the space that is normally occupied by the mandrel 12. By retracting the slips 30 into the interior of the centering sleeve 40 the dovetail shaped engaging surfaces 22 and 24 on the upper cone 18 and the lower cone 20 will be aligned with and can be engaged with the dovetail engaging surfaces 26 and 28, respectively, on the slips 30.

As best seen in FIG. 7, the dovetail engaging surfaces on the cones l8 and 20 have engaged the slips 30, and by moving the cones l8 and 20 toward each other, the slips 30 are moved out of the interior of the centering sleeve 40 and the mandrel 12 can then be inserted into the assembly and the thread 32 engages the upper cone 18. With the mandrel 12 in position, the slips can only be retracted until their backs rest on the exterior of the mandrel. And the cones l8 and 20 cannot be moved together sufficiently to allow the slips 30 to become disengaged therefrom in the extreme slip expanded position. Thus, with the mandrel 12 in position the slips 30 cannot become disengaged from the cones 18 and 20 regardless of whether they are moved to the extreme expanded or extreme retracted positions. The assembly 14 is disassembled by reversing the procedure. It is to be particularly noted that with the mandrel in position, all of the parts are positively locked together and cannot come apart. These parts, the upper cone l8, centering sleeve 40, all slips 30, lower cone 20 and mandrel 12, are fitted together in the interlocking fashion and are not held together by any removable means such as screws, or bolts and have the advantage that the tool will not come apart in a well hole accidentally.

In order to prevent the upper cone 18 from unthreading relative to the mandrel, as the tubing anchor is moved down a well casing, so as to cause the threads 32 to bind and lock the upper cone 18 in a retracted position such that the force of the bow springs 35 acting against a casing would not be sufficient to unlock the upper cone 18 and set the slips 30, a locking ring 52 is provided connected to the mandrel 12 and adjacent the upper cone 18. A pair of parallel pins 54 and 56 are provided, one being connected to the upper cone 18 and the other being connected to the locking ring 52 to prevent the cone 18 from rotationally unthreading and binding the threaded connection 32. However, the lead of the thread 32 is such that on one revolution of the cone 18 relative to the mandrel I2, the pins 54 and 56 will clear each other thereby allowing the cone I8 to be rotated in a direction to set the slips 30.

In use, the tubing anchor 10 is threadably attached to the tubing string I6 and run to the desired depth in a well. Left hand rotation of the tubing string causes the upper cone [8 and SIIPS 30 to move downwardly against the lower cone cones l8 and 20 being urged toward each other by the torque stored in the mandrel 12. The anchor 10 can be released by torquing the tubing 16 to the right and screwing the upper cone 18 away from the lower cone 20 thereby positively retracting the slips 30 by the dovetail connections between the slips 30 and the cones 18 and 20. In the event the tubing 16 cannot be turned to the right or the anchor 10 cannot be unscrewed, an upward pull of a predetermined amount will shear the pins 34 releasing the lower cone 20 from the mandrel l2 and allow the slips 30 to be retracted. However, the parts of the anchor 10 are all locked together and will not come apart in the hole accidentally and can only be taken apart by removing the mandrel 12.

The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned as well as others inherent therein.

What is claimed is:

l. A slip assembly for a well tool having a mandrel comprismg,

a plurality of unitary slips,

wedgeshaped slip supporting means surrounding the mandrel and positioned at each end of the slips whereby when the supporting means are moved relative to each other expand the slips outwardly,

integral dovetail shaped coacting engaging surfaces on each end of the slips and on the supporting means at the end of the slips,

a centering sleeve slidable at all times relative to and surrounding the mandrel, engaging means on the sleeve and each slip for maintaining the longitudinal movement of all of the unitary slips in unison as the slips are moved outwardly and inwardly,

said centering sleeve including an opening for each slip whereby said slips may be assembled to the supporting means by inserting the slips into the interior of the sleeve for aligning for dovetail engaging surfaces on the slips and on the supporting means.

2. The apparatus of claim I wherein the dovetail coacting engaging surfaces on the slips and on the supporting means remain in engagement at all times whereby the parts are interlocked together.

3. A tubing anchor comprising,

a tubular mandrel, the upper end of which is adapted to be connected to a well tubing,

an upper cone threadably engaged to the mandrel,

a lower cone mounted for rotation on the mandrel but longitudinally secured thereto,

friction means connected to the upper cone,

means between the upper cone and the mandrel for limiting upward movement of the cone relative to the mandrel,

a plurality of unitary slips positioned between the upper and lower cones,

integral dovetail shaped coacting engaging surfaces on each end of the slips and on the ends of the cones adjacent the slips,

a centering sleeve slidable at all times relative to and surrounding the mandrel, engaging means on the sleeve and each slip for maintaining the longitudinal movement of all of the unitary slips in unison as the slips are moved outwardly and inwardly,

said centering sleeve including an opening for each slip whereby said slips may be assembled to the cones by inserting the slips from the interior of the sleeve through the sleeve openings before the mandrel is inserted in the sleeve.

4. The apparatus of claim 3 wherein the lower cone is longitudinally secured to the mandrel by shear means. 

1. A slip assembly for a well tool having a mandrel comprising, a plurality of unitary slips, wedge-shaped slip supporting means surrounding the mandrel and positioned at each end of the slips whereby when the supporting means are moved relative to each other expand the slips outwardly, integral dovetail shaped coacting engaging surfaces on each end of the slips and on the supporting means at the end of the slips, a centering sleeve slidable at all times relative to and surrounding the mandrel, engaging means on the sleeve and each slip for maintaining the longitudinal movement of all of the unitary slips in unison as the slips are moved outwardly and inwardly, said centering sleeve including an opening for each slip whereby said slips may be assembled to the supporting means by inserting the sliPs into the interior of the sleeve for aligning for dovetail engaging surfaces on the slips and on the supporting means.
 2. The apparatus of claim 1 wherein the dovetail coacting engaging surfaces on the slips and on the supporting means remain in engagement at all times whereby the parts are interlocked together.
 3. A tubing anchor comprising, a tubular mandrel, the upper end of which is adapted to be connected to a well tubing, an upper cone threadably engaged to the mandrel, a lower cone mounted for rotation on the mandrel but longitudinally secured thereto, friction means connected to the upper cone, means between the upper cone and the mandrel for limiting upward movement of the cone relative to the mandrel, a plurality of unitary slips positioned between the upper and lower cones, integral dovetail shaped coacting engaging surfaces on each end of the slips and on the ends of the cones adjacent the slips, a centering sleeve slidable at all times relative to and surrounding the mandrel, engaging means on the sleeve and each slip for maintaining the longitudinal movement of all of the unitary slips in unison as the slips are moved outwardly and inwardly, said centering sleeve including an opening for each slip whereby said slips may be assembled to the cones by inserting the slips from the interior of the sleeve through the sleeve openings before the mandrel is inserted in the sleeve.
 4. The apparatus of claim 3 wherein the lower cone is longitudinally secured to the mandrel by shear means. 